Strap stretching device



Nov. 2, 1937. w- C cHlLDREss 2,097,444

STRAP STRETCHING DEVICE Original Filed Feb. l0, 1932 5 Sheets-Sheet 1Nov. 2, 1937. l w. c. CHILDREss 2,097,444

STRAP STRETGHING DEVICE Original Filed Feb. 10, 1932 'o' Sheets-Sheet 2Nov. 2, 1937. w, c, cHlLDREss 2,097,444

STRAP STRETCHING DEVICE;

Original Filed Feb. 10, 1932 5 Sheets-Sheet 3 Patented Nov. 2, 19372,091,444 g .STRAP s'rnE'ronrNo. DEVICE William C. Childress, Oak Park,Ill., assigner to Acme Steel Company, Chicago, Ill., a corporation ofIllinois Original application February 10. 1932, Serial No. 592,050.Divided and this application January 30, 1934, Serial No. 708,986.Renewed February 11 Claims. (Cl. 140-93) This invention relates toimprovements in strap stretching and sealing devices and the presentapplication is a division of my co-pending application Serial No.592,050, filed February 10, 1932,

5 in which there is disclosed a strap stretching and sealing deviceadapted to draw a exible metal strap taut around a box or package, cutoi the strap from the source of supply and then form an interlockingjoint between the overlapping l strap ends by cutting and shearing orotherwise deforming these portions of the strap. The present inventionrelatesA particularly to the means which are embodied in said device fordrawing the strap taut around the box or package preliminary to thecutting of the strap and the formation of the joint and the principalobject of the present invention is to provide improved mechanism forperforming this operation of stretching or drawing taut a exible strapor binder. A further object of the invention is to provide an improvedstrap stretching device comprising a base having mounted thereon a pairof gripping devices adapted to grip opposite end portions of the strapin combination with a slidably mounted bar carrying one of the grippingdevices and means for effecting relative movement of the bar and thebase for drawing the strap taut. A further object of the invention is toprovide a strap stretching device comprising means Afor engagingopposite end portions of a strap and effecting relative movement ofthese portions for drawing the strap taut in combination with means forautomatically terminating the tightening opera'tion when a predeterminedtension is obtained in the strap. Still another o bject of the inventionis to provide a strap stretching device comprising a base having mountedthereon a pair ofA relatively movable gripping devices adapted to engageopposite end portions of the strap in combination with mechanismcomprising a lever movable transversely to the direction in which thestrap extends for effecting movement of said gripping devices. Stillanother object of the invention is to provide a strapstretching deviceiii ed to function after a predetermined degreeof tension has beenbrought about in the strap. Other objects relate to various features ofconstruction and arrangement which will appear 50 more fullyhereinafter.

The nature of the invention will be understood from the followingspecification taken with the accompanying drawings in which oneembodiment is illustrated.

In the drawings,

comprising a yielding connection which is adapt- Figure 1 shows a sideelevation of a box or package with the improved strap stretching andsealing device of the present invention applied thereto for thepurposetof drawing a iiexible metal strap taut around the package;

Fig. 2 shows a top plan view of the overlapping ends of a metal straphaving formed therein the improved interlocking joint which is formed bythe operation of the device of the present inven- Fig. 3 shows a sideelevation of the joint illustrated in Fig. 2; I

Fig. 4 shows a bottom plan view of the joint illustrated in Fig. 2;

Fig. 5 shows an enlarged transverse section taken on the line 5-5 ofFig. 2;

Fig. 6 shows an enlarged transverse section taken on the line 6--6 ofFig. 2;

Fig. 7 shows an enlarged top plan view Aof the strap stretching andsealing device of the present invention with parts thereof broken away;

Fig. 8 is a detail sectional view taken on the line 8 8 of Fig'. 7;

Fig. 9 shows an enlarged front elevation of the strap stretching andsealing device illustrated in Figs. 1 and 7;

Fig. 10 is a detail vertical section taken on the line I0-I0 of Fig. 7;

Fig. 11 is a detail vertical section taken on the line II-II of Fig. 9;

Fig. 12 is a detail vertical section taken on the line IZ-IZ of Fig. 9;

Fig. 13 is a detail section taken on the line I3-I3 of Fig. 15;

Fig. 14 is an enlarged vertical section taken on the line lli-I4 of Fig.7, showing the position of the cutting blade or die and of the strapcrimping jaws preliminary to their engagement with the Fig. 15 is apartial vertical section similar to that of Fig. 14, showing the4relative positions of the parts after the strap has been cut off fromthe source of supply by the cutting die and after the crimping jaws havebeen brought into engagement with the straps;

y Fig. 16 is an enlarged vertical sectional view showing the positionsof the jaws after they have been brought into nal engagement with theoverlapping strap ends;

Fig. 17 is an enlarged detail horizontal section taken on the linei'I-i1 of Fig. 16;

Fig. 18 is an enlarged vertical section taken on the line Iii-,I8 ofFig. 17; and

Fig. 19 is a perspective view of one of the intermediate plates of thecrimping jaws.

It is common practice to employ at' flexible steel straps'or otherbinders for reenforcing boxes or packages and also for binding togethergroups of packages to form load` units and the present invention isdirected to improved means for drawing taut the strap or binder after ithas been passed around the package or group of packages, although it isillustrated in the accompanying drawings in association with the meansfor cutting ou the strap from the source of supply and the means forsubsequently crimping and also, preferably, shearing the overlappingstrap ends to form an interlocking joint, which features are describedandclaimed in the copending application above referred to. As illus-ltrated in Fig. 1. the strap stretching and sealing device I is shownapplied to the upper surface of a box or crate I I and the walls of thisbox are reenforced by two flat flexible steel straps or binders I2 whichare passed around the box. The strap stretching and sealing device I0 isshown in position to engage one of these straps.

The device I0 comprises a base plate I5 which is adapted to rest uponthe surface of the box or package and which carries the operating partby which the strap is rst stretched, then cut off from the source ofsupply and i'lnally crimped or otherwise deformed to form aninterlocking joint between the ends of the strap. The base plate I5 isprovided with a forwardly extending ange I6, spaced slightly above thesurface of the box, which is adapted to receive on its upper side thefree end I2a of the strap I2. Adjacent to the flange I6, the base platecarries an upwardly extending block or lug I1 which serves as a supportfor a gripping dog or detent I8 having a lower serrated or roughenedpart I8a which is adapted to coact with the upper side of the strapI2'to hold the strap firmly in engagement with the flange I6. Thegripping dog I8 is rotatably mounted upon a pin or shaft 20 which isfixed in the block I1 by means of a set screw 2I. 'I'he pin or shaft 20is provided with a relatively xed handle 22 which serves as a handle forthe detent I8 so that the latter may be moved out of engagement with theupper side of the strap against the compression of .a coil spring 23which is mounted in a recess in the detent and which engages at itsupper end a plug 24 mounted in an aperture in the upper flange |13 ofthe lug or block I1. This spring thus normally serves to maintain thedependent engagement with the strap and the serrated portion I8a of thedetent is displaced laterally from the pivotal axis of the detent, asshown in Fig. 9, so that a pull upon the strap I2 toward the left asviewed in that figure tends to increase the grip of the gripping dog andiiange upon the strap, while a movement of the strap in the otherdirection tends to effect an automatic release of thestrap from thegripping dog. After having the free end I2 of the strap passed intogripping engagement with the dog I8, the strap is passed around the boxor package II and the supply portion I2b of the strap is then carriedover the free end I2 and passed into engagement with a slotV I8b whichis formed in the side of the gripping dog I8 as shown particularly inFigs. 9 and 11. For the purpose of maintaining the supplyend of thestrapin engagement with this slot, the recess in which the spring 23 ismounted is provided'at its lower end with a movable ball 25 adapted toproject through a tapered aperture in the lower end of the recess sothat it is held by the spring 23 in engagement with the lower wall ofthe slot Ill to hold the strap in the slot while permitting the readyinsertion or withdrawal of the strap when desired.

For the purpose of stretching the strap I2 around the package, thesupply portion I2b thereof is engaged by another gripping dog 26 whichis carried by a block 21 mounted upon the outerend of a slidably mountedbar 28 carried by a plate I 5. This bar is adapted to move parallel tothe strap which is held by the gripping dog 2B against a flange 21*which projects forwardly from the block21. The block 21 is secured tothe bar 28 by a stud 29 and it carries a fixed pin or axle 30 upon whichthe gripping dog 28 is pivotally mounted. 'I'he upper edge of thegripping dog is curved to coact with the curved flange 2lb of the block.'I'his flange is concentric with the pin 38 so that the gripping dog issupported independently of the pin. The other end of the gripping dog isprovided with a serrated surface 26 which coacts with the upper side ofthe strap I2 and forces it against the flange 21l under the inuence of acoil spring 3| which engages a socket in the gripping dog and coactswith a flange 21c carried by the block 21. The gripping dog 26 isinclined toward the left as viewed in Fig. 9 so that a pull upon thestrap I2b toward the right will tend to increase the grip of the dogupon the strap while movement of the strap in the other direction willtend to effect an automatic release of the strap from the gripping dog.With the block 21 and the gripping dog 26 mounted as above described itwill be apparent that movement of these members with the bar 28 towardthe left, as view in Fig. 9, will draw the strap I2 taut around the boxor package II. The base plate I5 is provided on its upper side with agroove 32, of rectangular 'cross section, in which the bar 28 is adaptedto slide and the base plate is also provided with a recess 33 which isadapted to be engaged by the underside of the block 21, as shown in Fig.12, during the sliding movement of the bar 28. The bar is maintained inthe groove 32 by means of the retaining members 34 which are secured tothe base plate by screws 35, as shown in Fig. 7. 'I'he sliding movementof the bar 28 is eiected by certain operating mechanism comprising alink 31 which extends between two ears 38 carried by one of the members34, as shown in Fig. 10, and is secured thereto by means of a pivot pinor rivet 39. 'I'his link 31 has its other end pivotally -connected at 48with a shifting link 4I which has its forward end inserted between thebar 28 and the reversely bent portion 28 thereof, as shown in Fig. 10,being pivotally connected thereto by means of the pin 42. The pin 40carried by the link 31 thus provides a movable fulcrum about which thelever 4I is adapted to pivot in effecting a sliding movement of the bar28 and this pivotal movement of the lever 4I is effected through theconnections which are shown particularly in Figs. 14 and 15. The rearend of the lever 4I carries an upwardly extending pin 43 provided with aspherical head 43a. This pin is adapted to be inserted through akey-hole slot 44 formed in the wall of a hollow link 45 and the head 43ais engaged within the hollow link by a coil spring 46, the compressionof which may be adjusted by a plug 41 which threadedly engages the endof the link to coact with the end of the spring. The other end of thehollow link 45 is provided with another key-hole slot 48 to receive thehead 49a and the neck of a pin 49 which is secured to the short arm 50!of the strap stretching lever 50, the long arm of which extends upwardlyas shown in Fig. 9 with a handle 5I)b at the upper end thereof forengagement by the hand of the operator. The lever 5I! is fixed upon ashaft 5| which is journaled in bushings 52 secured by set screws 52awithin the spaced bearing members 53 and 54 mounted on or formedintegrally with the baseplate I5, as shown in Fig. 7. When the lever 50is moved rearwardly. or toward the left as view in Fig. 14, the hollowlink 45 is carried forwardly and this causes the spring 46 to move thepin 43 and thus actuate the lever 4| in a forward direction, causing thelatter lever to rock about the pin 40 so that it moves bodily from theposition shown by full lines in Fig. '1 to the position shown by dottedlines in that figure. This results in shifting the bar 28 toward theleft as viewed in Figs. 7 and 9 so that the strap 2 is thereby drawntaut. 'When a predetermined degree of tautness is obtained in the strapI2, the continued movement of the lever 50 will merely serve to compressthe spring 46 within the hollow link 45. During this movement of theoperating lever 4I, the rear end of that lever is maintained in positionadjacent to the -base I5 by a plate 55 which is secured by screws 56 toa ledge 51 formed on the base I5, with a part of the plate overlying aportion of the lever 4|, as shown particularly in Figs. '1 and 8. Animportant advantage of this construction is that the operation of thelever 50 produces arapid relative movement of the blocks I1 and 21during the early part'of the stretching operation when the strap iscomparatively slack, while the rapidity of motion decreases and theforce exerted upon the strap increases as the final stages of thestretching operation are approached. This permits the tool to be used instretching a strap in a single operation as compared with the use ofseveral tools or several operations, which has been the practiceheretofore.

After the strap has been drawn taut in the manner described above, theend portion |21 thereof is cut off from the source of supply and theoverlapping ends of the strap are then deformed to produce aninterlocking joint through the operation of certain mechanism carried bya movable head 59 comprising a pair of flat plates 60, spaced apart invertical planes, and having their rear ends pivotally mounted upon theshaft 5I as shown in Fig. '1. One plate 60 is maintained in frictionalengagement with the side of the bearing hub 53 by meansA of a coilspring 6| which is mounted on the shaft 5| with one end bearing againstthe last mentioned plate 60 and with the other end bearing against acollar 62 which is secured against endwise movement on the shaft 5| bymeans of a transverse pin 63. The other plate 60 is maintained againstthe bearing hub 54 by means of a plate 64 which is secured to the baseplate I5 by means of a screw 65. These plates 60 have mounted betweenthe enlarged forward ends thereof a pair of crimping jaws 66 which aremounted upona common pivot 61 extending between the plates and whichhave their arms 66n extending upwardly with their upper extremitiespivotally connected by when the head 59 is in its normal upper position,as shown in Figs. 9 and14 and, when the operator wishes to move the head59 downwardly that movement is first effected by thrusting on the lever1|, while maintaining it in its upright position and then, the lever 1Imay be turned about the pivot 'I2 for the purpose of actuating the links69 and thereby moving the jaws 66 toward each other to effect thecrimping and shearing of the stra ends as hereinafter more fullydescribed. The extent to which this pivotal movement of the lever 1| maybe carried is limited by means of a stop member 13 which threadedlyengages the lever 1|, being held in.

lever 1| is in its lowermost position, as shownin Fig. 16, thuspreventing further movement of the jaws 66 toward eachother. Byadjusting -the position of the stop member 13, the minimum separation ofthe jaws may be varied as desired. The initial downward movement of thehead 59 is utilized to effect the cutting 01T of the strap from thesource of supply. The cutting of the strap is effected by a cuttinglever 15 which is pivotally mounted on a pin 16 secured in one of theretaining members 34 previously referred to. As shown particularly inFigs. 13 and 14, this lever is provided on one side with a recess 15a inwhich is removably mounted the cutting blade or die 11, the die beingsecured to the lever by means of a screw 18. The die is adapted toextend downwardly past the vertical face of a stationary die 19 which iscarried by the adjacent member 34 and which extends forwardly therefromto underlie the upper portion I2b of the strap and to extend over theextremity I2a thereof. The lever 15 has an upwardly extending arm 15bwhich is pivoted at 80 to a link 8| pivotally mounted at 82 on theadjacent plate 60 of the head. It will be apparent that when the head 59moves downwardly, the link 8| will serve to actuate the cutting lever 15so that the movable cutting die 11 will be moved downwardly to engagethe supply portion I2b of the strap and cut it off by coaction with thestationary die 19, as shown in Fig. 13.

It is desirable to maintain the manually operated lever 1I in itsupright position and to prevent relative movement of the jaws 66 towardeach other until aftr the strap has been severed from the source of`supply and the jaws have been brought into a position wherein they mayembrace the overlapping strap ends. To obtain this result, the plate 64heretofore described has an arm 64*3L extending upwardly and forwardly.as shown in Fig. 14, with a curved surface 64b adapted to coact with theend of one of the links 69 along the surface which is concentric withthe axis of movement of the head 59. As a result of this arrangement,when the operator pushes downwardly on the lever 1| with this leverextending in an upward inclined position, as shown in Fig. 14, theinitial downward movement of the head 59 takes place without anyrelative movement of the jaws 66 due to the coaction of the link 69 withthe curved face 64b of the stationary plate. During this period ofmovement of the head 59 the cutting lever 15 is actuated to cut off thestrap and finally when a point is reached where the jaws 66 are in aposition to embrace the overlapping strap ends, as shown in Fig. 15, theend of the link 69 will have passed beyond the curved face 64b of the 75stationary plate so that the links may then separate from each othertoward the position shown in Fig. 16T/The lever 1I is then .permitted tomove angularly about its pivot 12 so that the jaws are actuated to crimpthe strap and shear its edges as hereinafter described, it beingunderstood that after the strap has been cut oi from the source ofsupply a portion of the upper end of the strap will overlie theextremity of the lower portion I2 so that when the head 59 ismoved-downwardly, 'these overlapping portions are forced together andare then operated upon to deform them into interlocking relation. OW-ing to the frictional engagement of the plate 60 with the bearinghubs-54 and 53, the head 59 is adapted to maintain any position in whichit may be put unless it is positively moved therefrom.

Referring now to the means for crimping and shearing the edges of theoverlapping portions of the strap to form an interlocking joint, it willbe seen upon referring to Figs. 16, 17 and 18 that each jaw comprises apair of side plates 85, a center plate 86, and two intermediate plates81, each of the latter plates being interposed between the center plateand one of the side plates. These plates' are secured together by rivets88 and the intermediate plates have parts 81b extended inwardly andmilled off on one side to intert with the corresponding parts of theopposite plates and to receive the pin 61 about which the jaws havepivotal movement.

The intermediate plates 81 have other parts 81a thereof extendedupwardly to form the arms 66a of the jaws which are connected to thelinks 69. 'I'he lower strap engaging portions of the jaws beneath thepivotal axis 61, are provided with parts adapted to receive and operateupon the overlapping ends of the strap I2. For this purpose, the edgesof the plates 85 of each jaw are provided with notches 85a ofrectangular cross section extending inwardly from `the upright face ofthe jaw and similar notches 86a of rectangular cross section extendinwardly from the edges of the center plate 86. The notch in each centerplate registers with the notches 85a in the plate 85 of the same jaw andthe notches in the plates of one jaw are disposed oppositely to thenotches in the plates of the other jaw so that they register with eachother when the jaws are closed upon each other as shown in Fig. 16. Theintermediate plates 81 are provided with notches 81c which are of curvedcross section and which register partially with the notches 85a and 86aof the respective jaws. The notches 81C, however, are of larger verticaldimensions and project below the openings of the notches 85a and 86a, asshown in Fig. 18. The side plates 60 of the head 59 are cut away asshown at 6I)a so that when the head 59 is lowered the openings 60aL areadapted to receive the overlapping ends of the strap and to hold theseoverlapping ends in a position wherein they may be engaged by thenotches of the jaws when these jaws are closed upon them by the movementof the lever 1I. A fiange 90 projects forwardly from the base I5 tosupport the extreme end of the portion I2a of the strap and the sideplates 60 of the head are adapted to engage the upper portion of thestrap and to bring the two parts of the strap into close overlappingrelation with each other with parts of the strap on opposite sides ofthe head supported from below by the flanges I6 and 90. The base I5 isfurther provided with a curved recess 9| extending inwardly from thespace between the flanges I6 and 90 to accommodate the lower portions ofthe jaws 66, as shown particularly in Fig. 16. The vertical dimensionsof the recesses 85 and 86a are such that they are closely tted by theoverlapping strap ends and the depth of the recesses is such that theyare completely occupied 'by the strap ends when the two jaws are closedupon each other, as shown in Fig. 16. The flat surfaces of the walls ofthese notches hold the strap ends in'a ilat condition'while the portionsof the strap between the plates 85 and the center plate 86 are curled orbeaded due to the action of the curved notches 81c which are formed inthe -plates'81. The side plates 85 and the center plate 86 serve to holdthe strap in such a position that the plates 81 will always curl orcrimp the edges of the strap in the same direction. The notches 85a and86a also serve to center the strap ends so that they receive the sameamount of curling or beading along each edge thereof. The plates 85 and86 also act as shearing dies to cooperate with the plates 81 in shearingthe overlapping portions of the strap at the ends of the curled orbeaded portions.

The action of these jaws 66 upon the overlapping ends of the strap isillustrated particularly in Figs. 2 to 6, inclusive, where the jointformed by the device is illustrated. As shown in these figures, thejoint '95 comprises the two overlapping strap ends I2a and I2b which aredeformed so that there is an intermediate at portion a, two end portions95b and two intermediate pairs of rolls or beads 95C which formindentations in the sides of the strap represented at 95d in Fig. 2. Thebeads or rolls 95 may be of more or less complete circular cross sectiondepending upon the formation of the recesses or notches 81c in theplates 81 and they have a telescoping engagement with each other so thatthey effectively prevent separation of the overlapping strap ends in anydirection transverse to the length of the strap. These beads or rollsalso have a longitudinal curvature, diverging away from each other onopposite sides of the strap ends so that they prevent relativelongitudinal movement of the strap ends, but this relative longitudinalmovement is further prevented by the shearing of the edges of the strapends to form inwardly extending cuts 95e at each end of each of thebeads. These cuts are formed by the cutting edges 81b of the plates 81which act as cutting dies so that when they engage the edges of thestrap the edges of the strap are sheared at the same time that theportions of the strap between the cuts or shears are turned inwardly toform the beads 95. These cuts 95e provide shoulders which coact with thetransversely extending shoulders on the ends of the beads to prevent anypossible relative endwise movement of the two overlapping strap ends. Asa result of the curling and shearing of the strap ends they are bowedupwardly to a slight extent in the region of the joint, as shown in Fig.4. In this way an effective joint is obtained without the use of anyenclosing sleeve or seal such as has heretofore been employed with manyforms of sealing devices. 'I'he form of seal or joint hereinabovedescribed is claimed in my co-pending application Serial No. 592,051,filed February 10, 1932.

In the operation of the device, the base plate I5 is seated upon thesurface of the box or package about which the strap I2 is to be secured,as shown in Fig. 1. The free end of the strap is then placed beneath thegripping dog I8 on the 75 lthe box or package, the supply portion I2bthereof is inserted beneath the gripping dog 26 and the ange 21a of themovable block 21, from which point the supply portion of the strapextends above the free end of the strap and through the slot |8h of thegripping dog I8 where it is held in place by the spring-pressed ball 25.The parts are then in readiness for drawing the strap taut, which iseffected by moving the lever 50 in a rearward direction, as shown inFig. 14, thereby causing a forward movement of the hollow link 45 with aresulting forward motion of the rear end oi. the lever 4| to whichmotion is imparted through the spring 46. As the lever 4| movesforwardly, its forward end swings toward the left. as viewed in Fig. 7,thereby actuating the sliding bar 28 upon which the block 21 is mounted.'I'he movement oi the block 21 carries with it the gripping dog 26 andflange 211 between which the supply portion of the strap is gripped sothat the strap is thereby drawn taut around the package. tautness isattained, the coil spring 46 within the hollow link is furthercompressed so that further movement of the lever 50 and hollow link 45will not effect any further tightening of the strap. The movable head 50is then swung downwardly toward the right, as viewed in Fig. 14, whileretaining the` lever 1| in its upright position. The initial motion ofthe head 59 is adapted to. cut off the strap from the source of supplydue to the actuation of the cutting lever 15 which engages the supplyportion of the strap seated on the ange 19. The cut-oi end of the strapis then pressed downwardly against the free end which rests upon theanges I6 and 90 and these overlapping ends then enter the notches 60a inthe side plates 60 of the head, as the downward motion of the head iscontinued. 'Ihe lever 1| is then swung forwardly about -its pivot 12with the result that the jaws- 66 are actuated to form telescoping beadsalong the edges of the overlapping` portions of the strap at pointswhich are spaced apart, as shown in Fig. 4, while at the same timeshearing the lateral edges of the strap ends, as shown at e, to insurefurther the security of the interlocking joint.

Although one form of the invention has been shown and described by wayof illustration, it will be understood that it may be constructed invarious other embodiments within the scope of the appended claims.

I claim:

1. The combination in a strap stretching device, of a pair of blockshaving relative linear movement, gripping means carried by said blocksfor gripping the opposite ends of a strap, and operating means formoving said blocks toward each other to draw said strap taut around apackage, said operating means comprising relatively movable partsadapted to yield after a predetermined tension has been set up in saidstrap.

2.`The combination in a strap stretching device, of a base plate, a pairof blocks carried by said base plate, one of said blocks being mountedfor sliding movement with respect to the other block, gripping meanscarried by said blocks for gripping the opposite ends of a strap, meansmovable transversely to said strap for actuating said movable block todraw said strap taut around a package, said last named means includingrela- When a predetermined degree of.

tively movable parts adapted to yield after a predetermined tension hasbeen set up in said strap.

3. The combination in a strap stretching device, of a base plate, astationary gripping device and a relatively movable gripping devicecarried by said base plate for gripping opposite end p0rtions of a strappassed around a package, one of said gripping devices being mounted forsliding movement on said base plate, and operating mechanism carried bysaid base plate for eiiecting relative movement of said grippingdevices, said operating mechanism comprising a yieldable connection topermit extension of said mechanism after a predetermined tension hasbeen created in said'strap.

4. The combination in a strap stretching device, of a base plate, a pairof gripping devices carried by said base plate for gripping opposite endportions of a strap, a bar upon which one of said gripping devices ismounted, said bar being slidably mounted upon said base plate, a linkpivoted on said bar, a lever having an intermediate part pivoted on saidlink and having one end pivoted on said bar, land operating mechanismconnected to the other end of said lever for effecting movement of saidbar.

5. The combination in a strap stretching device, oi' a base plate, apair of gripping devices carried by said base plate for grippingopposite end portions of a strap, a bar upon which one of said grippingdevices is mounted', said bar being slidably mounted upon said base, alink pivoted on said bar, a lever having an intermediate part pivoted onsaid link and having one end pivoted on said bar, and operatingmechanism connected to the other end of said lever for eecting movementof said bar, said mechanism including a resilient connection adapted toyield when a predetermined tension is obtained in the strap.

6. The combination in a strap stretching device, of a base, a pair ofgripping devices carried by said base, a bar slidably mounted on saidbase and having one of said gripping devices mounted thereon, levermechanism for effecting movement of said bar, and means for operatingsaid lever mechanism including a spring for permitting extension of saidmechanism after a predetermined tension has been created in the strap,

7. The combination in a strap stretching device, of a base, a pair ofgripping devices carried by said base, a bar slidably mounted on saidbase and having one of said gripping devices mounted thereon, levermechanism for eil'ecting movement of said bar, a hollow link connectedto said lever mechanism, means for effecting movement of said hollowlink, and a spring mounted in said hollow link and adapted to becompressed when said lever mechanism is actuated.

8. The combination in a strap stretching device, of a base, a pair ofgripping devices carried by said base, a bar slidably mounted on saidbase and having one of said gripping devices mounted thereon, a leverpivoted on said base and movable transversely to the direction ofmovement of said bar, operating mechanism connected between said leverand said bar for effecting movement of said bar to draw taut a strappassed around a package and held by said gripping devices, and means forcausing said operating mechanism to set up a predetermined tension insaid strap.

9. The combination in a strap stretching device, of a basea pair ofgripping devices carried by said base, a bar slidably mounted on saidbase and having one of said gripping devices mounted 75 thereon, a leverpivoted on said base and movable around a package and held by saidgripping detransversely to the direction of movement of said bar,operating mechanism connected between said lever and said bar foreffecting movement of said bar to draw taut a strap passed around apackage and held by said gripping devices parallel to the path ofmovement of said bar, and additional means carried by said base platefor cut- 'ting off said strap when it has been drawn taut.

10. The combination in a strap stretching device, of a base, a pair ofgripping devices carried by said base, a bar slidably mounted on saidbase and having one of said gripping devices mounted thereon, a leverpivoted on said base and movable transversely to the direction ofmovement of said bar, operating mechanism connected between said leverand said bar for effecting movement of said bar to draw taut a strappassed vices parallel to the path of movement of said bar, and a cuttingblade pivoted on said base plate and movable transversely to said strapfor cutting said strap off from the source of supply when it has beendrawn taut.

11. The combination in a strap stretching device, of a pair ofrelatively movable gripping devices adapted to\grip opposite endportions of a strap looped around an object to be. strapped, andoperating mechanism for effecting a relatively rapid relative movementof said gripping devices in the early stages of the stretching operationand for producing a decreasing rate of relative movement of said devicesas the strap approaches its taut condition.

WILLIAM C. CHILDRESS.

